Production of metallic uranium and alloys thereof



United States Patent .0

PRODUCTION OF METALLIC URANIUM AND ALLOYS THEREOF Alberto Cacciari, Ruggero De Leone, Carlo Fizzotti,

and Mario Gabaglio, all of Milan, Italy, assignors to C.I.S.E. Centro Informazi'oni Studi Esperienze S.-R.I., Milan, Italy, a firm No Drawing. Filed Sept. 3, 1957, Ser. No. 681,427

14 Claims. (Cl. 75-841) The present invention relates to a process for the production of metallic uranium or uranium alloys through thermic reduction of a uranium double fluoride by means of an alkaline or alkaline-earth metal or by means of aluminium.

Several methods are known for obtaining metallic uranium from thermic reduction of a uranium and sodium double fluoride, being desiccated at a temperature of 110 C., by means of metallic calcium.

It is also known that the uranium double fluorides that may be obtained by means of industrially eflicient methods have a relatively low apparent density, and that it is therefore difiicult to obtain a successful therrnic reduction, while said reduction is practically unattainable when having recourse to other metals, as for instance magnetisum and sodium.

The present invention has the object of making possible and controllable the thermic reduction of uranium double fluorides by means of any alkaline or alkalineearth metal or by means of aluminium, and is characterized by this, that the uranium double fluoride is subjected to a number of mechanical and thermic operations to the end of raising its apparent density with respect to the initial one, then it is mixed with the reducting element and the mixture is brought to react.

The uranium double fluorides to be reduced are.treated within limits of temperature which are comprised between 110 C. and the respective melting point of the salts. Dependently on the choice of said limits it is possible to control the form, or shape, of the resulting metal or alloy, form and shape that may vary from a fine powder up to a massive ingot.

The product that is obtained by means of the above mentioned operations may be either metallic uranium, if the reduction had been carried out by means of an alkaline or alkaline-earth metal, or a uranium alloy if the reduction had been made by means of aluminium, or else, if the reactive mixture had been previously mixed with an element capable of alloying with uranium, or with a compound of such an element, as for example a fluoride the reduction of which were suitable to take place together with the reduction of the uranium double fluoride.

The ways for bringing into reaction the mixture of uranium double fluorides, of the reducing element, and of some possibly added elements or compounds for obtaining an alloy, are depending either upon the composition of said mixture and upon the way that had been chosen for its preparation or dressing. More precisely, said mixture may be brought into reaction either by means of a total heating of the Whole mass of the reactive sub-- Example I 350 grams of uranium and calcium double fluoride, desiccated in air at a temperature of 200 C., and having an apparent density of 1.85 grams per cubic centimeter, are heated at a temperature of 450 C. in a stream of commercial nitrogen. The resulting product, ground into a suitable granulation and having an apparent density of 3.5 grams per cubic centimeter, is mixed with a quantity of metallic magnesium, in the form of a powder having a suitable granulometry, and in excess by 20 percent over the theoretical quantity. The mixture is introduced into a graphite container, which in its turn is contained into a sealed, metallic container, and is suitably tamped by vibration prior to sealing. The whole is made to react by heating at a temperature of 680 C. After cooling, the product appears in the form of finely subdivided uranium powder, surrounded by a scoria, or dross, of magnesium and calcium fluorides.

The yield of uranium metal is 95 percent.

Example II 3,000 grams of uranium and sodium double fluoride, desiccated in air at a temperature of 200 C. and having an apparent density of 1.55 grams per cubic centimeter, are melted in a graphite crucible in sealed containeri The resulting product, ground to a suitable granulometry and having an apparent density of 4.27 grams per cubic centimeter, is mixed with a quantity of metallic magnesium, in powder of a suitable granulation, exceeding by 15 percent the theoretical quantity. The mixture is'introduced into a graphite container which is contained in its turn into a sealed metallic container, and is suitably tamped by vibration before sealing. The whole is brought to reaction by heating at a temperature of 680 C. After cooling, the product appears in the form of a massive uranium ingot on the bottom of the'container and of an easily separable scoria, the ingot itself being'easily detachable from the graphite container.

The yield of massive uranium is 99 percent.

Example III 300 grams of uranium and sodium double fluoride, desiccated in air at a temperature of 200 C., are heated at a temperature of 450 C. in a stream of commercial nitrogen. The resulting product, ground to a suitable granulation and having an apparent density of 3.3 grams per cubic centimeter, is mixed with 36 grams of Zinc fluoride and with a quantity of metallic magnesium, in a powder having a suitable granulation, being in excess of 10 percent over the theoretical quantity. The mixture is introduced, and suitably tamped by pressing, into a sealed metallic container which is internally coated with a refractory material belonging in the class that comprises calcined dolomite, magnesium oxide or magnesium fluo ride.

The sealed container is brought to reaction by ignition of a uranium filament which is in contact with the top of the mixture. After cooling, the product appears in the form of a massive uranium ingot which is nearly free from zinc, and of a second metallic part which is composed of a magnetisum-zinc alloy almost without bra; nium, and of an easily separable dross.

The yield of uranium is percent.

It is of course understood that the practical details of the process and the quantitative data may differ from the examples hereinbefore described, without by this reason going out of the ambit of the invention as defined in the following claims.

We claim:

1. In the production of metallic uranium and uranium alloys by thermal reduction of a uranium double fluoride by heating with a reducing metal selected from the group consisting of alkali metals, alkaline earth metals and aluminum, the improvement comprising prior to the reduction, desiccating said uranium double fluoride and thereafter heating the uranium double fluoride to a temperature between about 200 C. and the melting point of the double fluoride for a period of time suflicient to substantially increase the apparent density of the double fluoride, mixing the double fluoride with the reducing metal, tamping the mixture by pressing, and thereafter heating the mixture until reaction is initiated.

2. In the production of metallic uranium and uranium alloys by thermal reduction of a uranium double fluoride by heating with a reducing metal selected from the group consisting of alkali metals, alkaline earth metals and aluminum, the improvement comprising prior to the reduction, desiccating said uranium double fluoride in a stream of air at a temperature suflicient to dry said uranium double fluoride and thereafter heating the uranium double fluoride to a temperature between about 200 C. and the melting point of the double fluoride for a period of time sufficient to substantially increase the apparent density of the double fluoride, mixing the double fluoride with the reducing metal and with an element capable of alloying with uranium, tamping the mixture by pressing, and thereafter heating the mixture until reaction is initiated.

3. In the production of metallic uranium and uranium alloys by thermal reduction of a uranium double fluoride by heating with a reducing metal selected from the group consisting of alkali metals, alkaline earth metals and aluminum, the improvement comprising prior to the reduction, desiccating said uranium double fluoride in a stream of air at a temperature suflicient to dry said uranium double fluoride and thereafter heating the uranium double fluoride to a temperature between about 200 C. and the melting point of the double fluoride for a period of time suflicient to substantially increase the apparent density of the double fluoride, mixing the double fluoride with the reducing metal and with a fluoride of an element capable of reduction by said reducing metal, tamping the mixture by pressing, and thereafter heating the mixture until reaction is initiated.

4. In the production of metallic uranium and uranium alloys by thermal reduction of a uranium double fluoride by heating with a reducing metal selected from the group consisting of alkali metals, alkaline earth metals and aluminum, the improvement comprising prior to the reduction, desiccating said uranium double fluoride in a stream of air at a temperature suflicient to dry said uranium double fluoride and thereafter heating the uranium double fluoride to a temperature between about 200 C. and the melting point of the double fluoride for a period of time suflicient to substantially increase the apparent density of the double fluoride, mixing the double fluoride with the reducing metal and with a substance capable of reacting with the reducing metal with the production of heat, tamping the mixture by pressing, and thereafter heating the mixture until reaction is initiated.

5. In the production of metallic uranium and uranium alloys by thermal reduction of a uranium double fluoride by heating with a reducing metal selected from the group consisting of alkali metals, alkaline earth metals and aluminum, the improvement comprising prior to the reduction, desiccating said uranium double fluoride in a stream of air at a temperature suflicient to dry said uranium double fluoride and thereafter heating the uranium double fluoride to a temperature between about 200 C. and the melting point of the double fluoride for a period of time suflicient to substantially increase the apparent density of the double fluoride, mixing the double fluoride with the reducing metal and with iodine, tamping the mixture by pressing, and thereafter heating the mixtureuntilv reaction is initiated.

6. In the production of metallic uranium and uranium alloys by thermal reduction of a uranium double fluoride by heating with a reducing metal selected from the group consisting of alkali metals, alkaline earth metals and aluminum, the improvement comprising prior to the reduction, desiccating said uranium double fluoride in a stream of air at a temperature sufficient to dry said uranium double fluoride and thereafter heating the uranium double fluoride to a temperature between about 200 C. and the melting point of the double fluoride for a period of time suflicient to substantially increase the apparent density of the double fluoride, mixing the double fluoride with pulverized metallic magnesium, tamping the mixture by pressing, and thereafter heating the mixture until reaction is initiated.

7. In the production of metallic uranium and uranium alloys by thermal reduction of a uranium double fluoride by heating with a reducing metal selected from the group consisting of alkali metals, alkaline earth metals and aluminum, the improvement comprising prior to the reduction, desiccating said uranium double fluoride in a stream of air at a temperature suflicient to dry said uranium double fluoride and thereafter heating the uranium double fluoride to a temperature between about 200 C. and the melting point of the double fluoride for a period of time suflicient to substantially increase the apparent density of the double fluoride, mixing the double fluoride with pulverized metallic magnesium and zinc fluoride, tamping the mixture by pressing, and thereafter heating the mixture until reaction is initiated.

8. In the production of metallic uranium and uranium alloys by thermal reduction of a uranium double fluoride by heating with a reducing metal selected from the group consisting of alkali metals, alkaline earth metals and aluminum, the improvement comprising prior to the reduction, desiccating said uranium double fluoride in a stream of air at a temperature sufficient to dry said uranium double fluoride and thereafter heating the uranium double fluoride to a temperature between about 200 C. and the melting point of the double fluoride for a period of time suflicient to substantially increase the apparent density of the double fluoride, mixing the double fluoride with metallic sodium, tamping the mixture by pressing, and thereafter heating the mixture until reaction is initiated.

9. In the production of metallic uranium and uranium alloys by thermal reduction of a uranium double fluoride by heating with a reducing metal selected from the group consisting of alkali metals, alkaline earth metals and aluminum, the improvement comprising prior to the reduction, desiccating said uranium double fluoride in a stream of air at a temperature suflicient to dry said uranium double fluoride and thereafter heating the uranium double fluoride to a temperature between about 200 C. and the melting point of the double fluoride for a period of time sufficient to substantially increase the apparent density of the double fluoride, mixing the double fluoride with metallic sodium and zinc fluoride, tamping the mixture by pressing, and thereafter heating the mixture until reaction is initiated.

10. In the production of metallic uranium and uranium alloys by thermal reduction of a uranium double fluoride by heating with a reducing metal selected from the group consisting of alkali metals, alkaline earth metals and aluminum, the improvement comprising prior to the reduction, desiccating said uranium double fluoride in a stream of air at a temperature suflicient to dry said uranium double fluoride and thereafter heating the uranium double fluoride to a temperature between about 200 C. and the melting point of the double fluoride for a period of time suflicient to substantially increase the apparent density of the double fluoride, mixing the double fluoride with the reducing metal, tamping the mixture by pressing, and thereafter heating the mixture in a sealed container internally coated with a refractory material selected from the group consisting of calcined dolomite,

magnesium oxide and magnesium fluoride until reaction is initiated.

11. A method of producing metallic uranium Which comprises desiccating in air at a temperature of about 200 C. a uranium calcium double fluoride salt having an apparent density of about 1.85 grams per cubic centimeter, heating said desiccated salt in a stream of nitrogen at a temperature of about 450 C. and grinding said salt to thereby increase the apparent density of said salt to about 3.5 grams per cubic centimeter, mixing said ground salt with about 20% excess over the theoretical quantity of pulversized metallic magnesium, introducing said mixture into a graphite container which is placed into a sealed metallic container, tamping said mixture prior to closing said sealed container, and reacting said mixture by heating said sealed container to a temperature of about 680 C.

12. A method of producing metallic uranium which comprises, desiccating in air at a temperature of about 200 C. a uranium sodium double fluoride salt having an apparent density of about 1.55 grams per cubic centimeter, melting said desiccated salt in a graphite crucible contained in a sealed container and grinding said melted salt after it has cooled to thereby increase the apparent density of said salt to about 4.27 grams per cubic centimeter, mixing said ground salt with about 15% excess over the theoretical quantity of pulverized metallic magnesium, introducing said mixture into a graphite container which is placed into a sealed metallic container, tamping said mixture prior to closing said sealed container, and reacting said mixture by heating said sealed container to a temperature of about 680 C.

13. A method of producing metallic uranium which comprises, desiccating in air at a tempenature of about 200 C. a uranium sodium double fluoride salt, heating said desiccated salt in a stream of nitrogen at a temperature of about 450 C. and grinding said salt to thereby obtain a uranium sodium double fluoride salt having an apparent density of about 3.3 grams per cubic centimeter, mixing said ground salt with Zinc fluoride and pulverized metallic magnesium, the quantity of said magnesium being by about 10% over the theoretical quantity, introducin-g said mixture into a sealed container lined with a suitable refractory material, tamping said mixture prior to closing said sealed container, reacting said mixture, and priming the reaction of said mixture by the ignition of a uranium filament Which is in contact With said mixture.

14. In the production of metallic uranium and uranium alloys by thermal reduction of a uranium double fluoride With a reducing metal selected from the group consisting of alkali metals, alkaline earth metals and aluminum, the improvement comprising prior to the reduction, desiccating the uranium double fluoride in air at a temperature suflicient to dry said uranium double fluoride, thereafter heating said double fluoride in a stream of nitrogen to a temperature between about 200 C. and

the melting point of said double fluoride for a period of time suflicient to substantially increase the apparent density of the double fluoride, grinding it, mixing it with the reducing metal, and thereafter heating the mixture until reaction is initiated.

References Cited in the file of this patent UNITED STATES PATENTS 1,728,942 Marden Sept. 24, 1929 1,814,721 Marden July 14, 193 1 2,785,064 Wilhelm Mar. 12, 1957 OTHER REFERENCES 

1. IN THE PRODUCTION OF METALLIC URANIUM AND URANIUM ALLOYS BY THERMAL REDUCTION OF A URANIUM DOUBLE FLORIDE BY HEATING WITH A REDUCING METAL SELECTED FROM THE GROUP CONSISTING OF ALKALI METALS, ALKALINE EARTH METALS AND ALUMINUM, THE IMPROVEMENT COMPRISING PRIOR TO THE REDUCTION, DESICCATING SAID URANIUM DOUBLE FLUORIDE AND THEREAFTER HEATING THE URANIUM DOUBLE FLUORIDE TO A TEMPERATURE BETWEEN ABOUT 200*C. AND THE MELTING POINT OF THE DOUBLE FLUORIDE FOR A PERIOD OF TIME SUFFICIENT TO SUBSTANTIALLY INCREASE THE APPARENT DENSITY OF THE DOUBLE FLUORIDE, MIXING THE DOUBLE FLUORIDE WITH THE REDUCING METAL, TAMPING THE MIXTURE BY PRESSING, AND THEREAFTER HEATING THE MIXTURE UNTIL REACTION IS INITIATED. 